1. Technical Field
The present invention relates to a connecting structure and a connecting method of a pressure attaching terminal to an electric wire.
2. Background Art
As an electric wire to which a terminal is attached under pressure, a multi-core electric wire having many core wires twisted together is ordinarily used (for instance, see JP-UM-A-6-31072). However, a problem arises that as a sectional area of a conductor is larger, the number of the core wires to be used is increased in the multi-core electric wire, so that a cost is high. Accordingly, for the electric wire used in a part which does not require a bending property, an inexpensive single core electric wire is desired to be used in place of the multi-core electric wire.
FIGS. 2A to 2C are diagrams for explaining a usual problem when a terminal is attached under pressure to a single core electric wire. FIG. 2A is a sectional view showing a state before the terminal is attached under pressure to the single core electric wire. FIG. 2B is a sectional view showing a state after the terminal is attached under pressure to the single core electric wire. FIG. 2C is a sectional view showing a state that a pressure attached part creeps by receiving a repeated load of high temperature and low temperature.
In FIG. 2A to FIG. 2C, reference numeral 10A designates a single core electric wire, 11A designates a single core conductor and 12 designates a coat which covers the single core conductor 11A. Further, reference numeral 20 designates a pressure attaching terminal, 21 designates a bottom plate part, 22 designates an electric wire connecting part and 22a designates an electric wire caulking piece. As shown in FIG. 2A, the pressure attaching terminal 20 has, in its front part, an electric connecting part (an illustration is omitted) connected to a mate side terminal, and in its rear part, the electric wire connecting part 22 formed substantially in the shape of U in section and including the bottom plate part 21 and one pair of electric wire caulking pieces 22a which are extended upward from both side edges of the bottom plate part 21 and bent inside to enclose a terminal part of the electric wire to be connected so that the electric wire caulking pieces caulk the terminal part of the electric wire so as to come into close contact with an upper surface of the bottom plate part 21.
When the pressure attaching terminal 20 is connected to the single core electric wire 10A, as shown in FIG. 2B, the signal core conductor 11A exposed by removing the coat 12 is set on the bottom plate part 21 of the electric wire connecting part 22. Under this state, the one pair of electric wire caulking pieces 22a of the electric wire connecting part 22 are bent inside to caulk the single core conductor 11A. Thus, the pressure attaching terminal 20 is attached under pressure and fixed to the terminal part of the single core electric wire 10A.